3 simple design tips that will make your home look like it was decorated by a pro

• To make a room look larger, hang your curtains above your window.• Group in odd numbers for an appealing decorative trick.• Paint your ceiling for an subtle style.

Sometimes, a so-called "trick" (or, yes, "hack") comes along that's so truly effective you buy all in and never look back. (We feel this way about softening butter more speedily by smacking it with a rolling pin!) It then transforms from trick to rule—the best way, rather than just an alternative or something to consider. The same ascent happens in interior design trends: Someone has (or spots) a good idea, calls it out, and it gains such widespread support that it eventually feels universally agreed-upon.

Of course the very best rules are the most fun to break (nobody knows better than us), but they're good to turn to if you're feeling uninspired, or directionless. (How do I make this room feel bigger? Where does this curtain rod go?) So here are three interior design tricks-turned-rules that you can depend on when decorating a space.

Hang your curtain rod well above the window.

Rather than just run your curtain rod along the top of the window casing, mount it instead at least six inches higher on the wall—even so far as to be closer to the ceiling than the frame itself.

The effect is elongating, and so much so that not raising the rod up this way will cause the curtains to look stubby and cramped.

For a balanced, but not-too-perfect, style...

Group furniture and accents in threes.

Getty Images

Why? Because groupings of odd numbers are simply more visually appealing. Your mantle vignette, grouping of tchotchkes heaped atop a dresser, and cluster of paintings will feel more finished, more casually impactful, than if you stop at two (or move past to four!).

(There are always exceptions to this one, of course, but it's a good rule of thumb to lean on if you're arranging and can't seem to pull off the right look.)

To give a room a finished look...

Paint your ceiling.

Wayfair/Stephen Busken

If your ceiling is already a bright, clean, airy white when you move in—lucky you! That's going to keep the room feeling open and will really look fine with any paint choice on the walls.

But if you move in to a yellowy-white, or anything colorful that you didn't choose, paint it. "It's such an overlooked move, but for me a room isn't finished until the ceiling has been considered," designer Chloe Redmond Warner says.ct

Some alternatives to white are:

Match the walls. For an enveloping, cozy feel, use the same color on your ceiling as you do the walls.

Go slightly lighter than the wall color. You'll get more depth and dimension from your color choice without introducing too many variables.

Choose an entirely different color (or pattern!) than the walls.The result will be bold and graphic—so save this for when you're aiming for high-impact.